As sft says, the green lines are created by the mowing. If you are laying a lawn from scratch, don't rush it. Like most things, laying the turf (much simpler than growing it from seed) is the easy bit. All the work is in the preparation. My wife and I spent about 6 weekends levelling, raking, de-stoning and treading the subsoil before the actual 4 hours of turf laying(approx 100 sq. m.). Persevere;it's worth it in the end. Also, don't buy your turf from your local DIY, you don't know how long it has been there. Turf should be laid as soon as possible after cutting. I would recommend Rolawn, who are based in Yorkshire but have depots all over the country. You should be able to order it fresh cut to your door. It is worth the extra �1/sq.m. to have it fresh. Any other advice on turf laying, post on here and I'll be happy to give you any pointers.